1. Technical Field
The present invention relates to a liquid ejection device, a printing device, and the like.
2. Related Art
Like an ejection head mounted on an inkjet printer, there are many actuators composed of a capacitive load such as a piezoelectric element. For driving the actuator as a capacitive load, a drive signal at a certain level of power is needed. Therefore, the drive signal is generated by power-amplifying a drive waveform signal as the source of the drive signal. In this case, when an analog drive waveform signal is power-amplified in an analog manner to directly generate an analog drive signal, power efficiency is reduced because a large power loss occurs. Therefore, a technique of performing power amplification using a so-called class-D amplifier has been proposed.
When using a switching circuit such as a class-D amplifier, a bypass capacitor is generally arranged between a power supply potential and a ground potential for suppressing the ringing of output voltage (for example, JP-A-2011-187809 (Patent Document 1)). In inkjet printers, the occurrence of ringing leads to the occurrence of EMI noise. As a result, the discharge amount of ink varies, which is obstructive to an improvement in print quality.
It is important for suppressing the ringing to reduce the wire impedance of a loop formed of two transistors and a bypass capacitor that constitute a switching circuit. In a multilayer wiring board shown in FIGS. 1 and 2 of Patent Document 1, a wire has to be routed around via conductors, which is a cause of increasing the wire impedance of the loop formed of the two transistors and the bypass capacitor that constitute the switching circuit. For this reason, when the multilayer wiring board disclosed in Patent Document 1 is used for a printing device or the like, there are limitations to suppress ringing, that is, to improve print quality.